Fix visibility of rcube_ldap_exop_password::$debug (#6828)

plugins/password/drivers/ldap_exop.php

@@ -31,8 +31,6 @@ require_once __DIR__ . '/ldap_simple.php';
 
 class rcube_ldap_exop_password extends rcube_ldap_simple_password
 {
-    private $debug = false;
-
     function save($curpass, $passwd)
     {
         if (!function_exists('ldap_exop_passwd')) {

plugins/password/drivers/ldap_ppolicy.php

@@ -12,6 +12,8 @@
 
 class rcube_ldap_ppolicy_password
 {
+    protected $debug = false;
+
     public function save($currpass, $newpass, $username)
     {
         $rcmail = rcmail::get_instance();